function XMLHTTPRequest() { 
        var http = 0;
        if (window.XMLHttpRequest) {
                http = new XMLHttpRequest();
        } else {
                try { 
                        http = new ActiveXObject("Msxml2.XMLHTTP");
                } catch(e) {
                        try { 
                        http = new ActiveXObject("Microsoft.XMLHTTP");
                        } catch(e) { 
                                http = false; 
                        } 
                }
        } 
        return http; 
}

function mostrar_pagina(url, div) {
        var http = XMLHTTPRequest();
        if (http) {
                http.onreadystatechange = function() {
                        if (http.readyState == 4) {
                                if (http.status == 200) {
                                        var retorno = unescape(http.responseText.replace(/\+/g," "));
                                        document.getElementById(div).innerHTML = retorno
                                } else {
                                        alert('There was a problem with the request.');
                                }
                        }               
                }
                http.open('GET', url, true);
                http.send(null);
        }
        else {
                alert('Erro seu navegador nao suporta ajax');
        }
}       

function addEvent(obj, evType, fn) {
        if (typeof obj == "string") {
                if (null == (obj = $(obj))) {
                        throw new Error("Cannot add event listener: HTML Element not found.");
                }
        }
        if (obj.attachEvent) {
                return obj.attachEvent(("on" + evType), fn);
        } else if (obj.addEventListener) {
                return obj.addEventListener(evType, fn, true);
        } else {
                throw new Error("Your browser doesn't support event listeners.");
        }
}

function iniciar() {    

var items = [], allItems = document.getElementsByTagName("li");
        
for (var i = 0; i < allItems.length; i++) {                             
        allItems[i].onclick = function() {      
                for (var item = this.parentNode.firstChild; item; item = item.nextSibling) {            
                        item.className = 'normal';                      
                }
                this.className = 'current';                             
                var padrao = /(<span(.*?)>(.*?)<\/span>)/i;     
                var pagina = this.innerHTML.replace(padrao, "$3");      
                var url = 'receber.php?pagina=' + pagina;                                               
                mostrar_pagina(url, 'conteudo');                                                
                document.title = pagina;                
        }                               
}       

var aba = document.getElementsByTagName("span");

        for (var j = 0; j < aba.length; j++) {          
                aba[j].onmouseover = function() {               
                        if(this.className != 'link'){                                   
                                this.className = 'link';
                        }       
                }               
                aba[j].onmouseout = function() {        
                        if(this.className != 'normal'){         
                                this.className = 'normal';
                        }       
                }
        }       
}

// quando terminar o carregamento da página, executa a "iniciarMudancaDeEnterPorTab"
addEvent(window, "load", iniciar);